In-Situ EMF Measurements of Rooftop Attenuation for Assessment of the Compliance Boundary of Cellular Base Stations

In this paper, in-situ electromagnetic field (EMF) measurements for investigating the electromagnetic attenuation of concrete-made flat rooftops are presented for the first time. In total ten rooftop sites were chosen to measure various types with different covers and construction variants. Considering the rooftop attenuation in the EMF-assessment can reduce the compliance boundary in vertical dimension of cellular sites with 4G or 5G NR radio systems, as the public area is typically below the rooftop. For precise measurement of the rooftop attenuation a measurement methodology is presented, which uses existing mobile radio signals. The measured rooftop attenuation values range from 12dB to 40dB for frequencies between 816MHz and 3654MHz including 4G and 5G and are dependent on the concrete thickness and rooftop cover. In addition, measurements of larger openings such as dome rooflights, which can decrease the rooftop attenuation in worst-case scenarios to nearly zero dB, are presented.